Drive apparatus for tape-like optical recording medium

ABSTRACT

An apparatus for driving a tape-shaped optical recording medium, which comprises a supply reel ( 41 ) for supplying an optical tape ( 40 ), a take-up reel ( 42 ) for taking-up the optical tape ( 40 ), a friction capstan ( 43 ) for driving the optical tape ( 40 ) to run to the take-up reel ( 42 ) from the supply reel ( 41 ) and a running guide member ( 46 ) for guiding the optical tape ( 40 ) running between the supply reel ( 41 ) and the take-up reel ( 42 ). The running guide member ( 46 ) has a flat portion forming a guide face portion ( 70 ) for facing to the optical tape ( 40 ) is operative to cause the optical tape ( 40 ) to run along the flat portion. Thereby, an area on the guide face portion ( 70 ) of the running guide member ( 46 ) where an incident position on the optical tape ( 40 ) of a light beam is fixed invariably can be stably maintained to be relatively wide.

TECHNICAL FIELD

The invention disclosed in each of claims of the present applicationrelates to an apparatus for driving a tape-shaped optical recordingmedium on which information is recorded by a light beam incidentthereupon or from which recorded information is read by a light beamincident thereupon.

TECHNICAL BACKGROUND

In the field of information recording on a recording medium andinformation reproduction from a recording medium on which theinformation is recorded, under the circumstances wherein recording andreproduction of data representing moving pictures performed with arelatively small-scale recording and reproducing instrument are desired,it is strongly required more than before to have arrangements forrecording information on a recording medium with high data density,increasing data rate of information to be recorded on or reproduced froma recording medium and so on. Accordingly, with the intention of meetingsuch requirements, there has been proposed an optical recording andreproducing technology for causing a single or a plurality of lightbeams to be incident upon an optical recording medium on whichinformation can be recorded with light so as to record information onthe optical recording medium and to reproduce information from theoptical recording medium on which the information is recorded.

With the optical recording and reproducing technology, in addition tothe advantage that noncontact information recording wherein informationis subjected to noncontact recording on an optical recording medium ornoncontact information reproduction wherein information recorded on anoptical recording medium is subjected to noncontact reproduction fromthe optical recording medium is carried out, further advantages that alaser light beam is used for recording information on an opticalrecording medium so that the information is recorded with high datadensity on the optical recording medium and a plurality of independentlaser light beams are used for recording information on and reproducingthe information from an optical recording medium so that the data rateof the information to be recorded on or reproduced from the opticalrecording medium is increased, are obtained. As one of informationrecording and reproducing apparatus, to each of which such opticalrecording and reproducing technology as mentioned above is applied, anoptical tape recording and reproducing apparatus in which a tape-shapedoptical recording medium, namely, an optical tape is used, has beenproposed as disclosed in the paper of “Novel digital optical taperecorder”, Oakley, William S., LaserTape Inc., SPIE Proceedings Vol.2604, pp. 256–262.

FIG. 1 shows a light beam controlling and signal processing portion ofan example of the optical tape recording and reproducing apparatusproposed previously. In the light beam controlling and signal processingportion shown in FIG. 1, a laser light source 1 is provided forgenerating continuously a single laser light beam as a parallel lightbeam. The single laser light beam emitted from the laser light source 1enters into a beam producing hologram 2.

In the beam producing hologram 2, the single laser light beam which isthe parallel light beam emitted from the laser light source 1 is dividedinto a plurality of laser light beams each being a parallel light beam.That is, the beam producing hologram 2 is operative to produce aplurality of parallel light beams by dividing the single parallel lightbeam.

The laser light beams obtained from the beam producing hologram 2 enterinto a polarized light beam splitter 3 and are reflected from thepolarized light beam splitter 3 to be directed downward in FIG. 1 topass through a quarter wavelength plate 4 and then enter into aconverging lens 5. The converging lens 5 is operative to converge thelaser light beams having passed through the quarter wavelength plate 4on a two-dimensional light-modulator 6.

The two-dimensional light-modulator 6 is constituted with a plurality ofreflection type light-modulating elements which are arrangedtwo-dimensionally with predetermined spaces. The laser light beamsconverged by the converging lens 5 come respectively to the reflectiontype light-modulating elements so arranged two-dimensionally as to formthe two-dimensional light-modulator 6. A back surface of each of thereflection type light-modulating elements, which is opposite to anincident surface of the reflection type light-modulator upon which oneof the laser light beams is incident, forms a light reflector.Therefore, the laser light beam incident upon each of the reflectiontype light-modulating elements is reflected from the light reflector inthe form of the back surface of the reflection type light-modulator.

In relation to the two-dimensional light-modulator 6, a modulationcontrol signal generator 7 is provided. The modulation control signalgenerator 7 is operative to produce a plurality of modulation controlsignals SM corresponding to information which are to be recorded andsupply the reflection type light-modulating elements constituting thetwo-dimensional light-modulator 6 with the modulation control signalsSM, respectively. Each of the reflection type light-modulating elementsconstituting the two-dimensional light-modulator 6 is operative tomodulate the laser light beam which is incident thereupon and reflectedtherefrom in response to the modulation control signal SM. Themodulation of the laser light beam in the two-dimensionallight-modulator 6 is carried out by varying the reflection amount of thelaser light beam at each of the reflection type light-modulatingelements in response to the modulation control signal SM. Incidentally,if the modulation control signals SM require, the laser light beam whichis incident upon each of the reflection type light-modulating elementsconstituting the two-dimensional light-modulator 6 is reflected from thereflection type light-modulating elements substantially without beingmodulated.

As a result of this, the laser light beams which are modulated inresponse to the modulation control signals SM at and reflected from thereflection type light-modulating elements arranged two-dimensionallywith predetermined spaces, respectively, or reflected respectively fromthe reflection type light-modulating elements arranged two-dimensionallywith predetermined spaces substantially without being modulated, areobtained from the two-dimensional light-modulator 6 to be directed tothe converging lens 5.

The laser light beams from the two-dimensional light-modulator 6 passthrough the converging lens 5 and the quarter wavelength plate 4 toenter into the polarized light beam splitter 3. Since the laser lightbeams entering into the polarized light beam splitter 3 from the quarterwavelength plate 4 have passed through the quarter wavelength plate 4twice in the direction to the converging lens 5 and in the oppositedirection to the polarized light beam splitter 3, a plane ofpolarization of each of the laser light beams entering into thepolarized light beam splitter 3 from the quarter wavelength plate 4 hasbeen rotated by 90 degrees in comparison with that of each of the laserlight beams entering into the polarized light beam splitter 3 from thebeam producing hologram 2 and therefore the laser light beams enteringinto the polarized light beam splitter 3 from the quarter wavelengthplate 4 pass through the polarized light beam splitter 3 without beingreflected.

The laser light beams thus having passed through the polarized lightbeam splitter 3 further pass through a quarter wavelength plate 8 and alight beam control optical system 9 to be incident upon an optical tape10 which is an optical recording medium. The light beam control opticalsystem 9 is operative to subject each of the laser light beams passingthrough there to the optical tape 10 to focus control for focusingproperly each of the laser light beams on the optical tape 10 andtracking control for causing each of the laser light beams to beincident upon a proper position on the optical tape 10. Further, theoptical tape 10 is driven by an optical tape driving device not shown inFIG. 1 to run in the direction indicated with an allow T (hereinafter,referred as the T direction).

With the movement of the optical tape 10 in the T direction, a pluralityof recording tracks, on each of which information is recorded, areformed on the optical tape 10 along the moving direction of the opticaltape 10.

When the laser light beams which have been reflected without beingmodulated from the two-dimensional light-modulator 6 are incident uponthe optical tape 10, these laser light beams are modulated in responseto information recorded on the optical tape 10 and simultaneouslyreflected from the optical tape 10 to be directed to the light beamcontrol optical system 9. The laser light beams obtained from theoptical tape 10 pass through the light beam control optical system 9 andthe quarter wavelength plate 8 and then enter into the polarized lightbeam splitter 3. Since the laser light beams entering into the polarizedlight beam splitter 3 from the quarter wavelength plate 8 have passedthrough the quarter wavelength plate 8 twice in the direction to thelight beam control optical system 9 and in the opposite direction to thepolarized light beam splitter 3, a plane of polarization of each of thelaser light beams entering into the polarized light beam splitter 3 fromthe quarter wavelength plate 8 has been rotated by 90 degrees incomparison with that of each of the laser light beams entering into thepolarized light beam splitter 3 from the quarter wavelength plate 4 andtherefore the laser light beams entering into the polarized light beamsplitter 3 from the quarter wavelength plate 8 are reflected from thepolarized light beam splitter 3 to be directed to the right in FIG. 1.

The laser light beams reflected to the right in FIG. 1 from thepolarized light beam splitter 3 enter into a light beam splitter 11. Apart of each of the laser light beams having entered into the light beamsplitter 11 is reflected from the light beam splitter 11 to be directeddownward in FIG. 1 to pass through an optical element 12, such as acylindrical lens or the like, and then enters into a focus and trackingdetector 13 and another part of each of the laser light beams havingentered into the light beam splitter 11 passes through the light beamsplitter 11 further to pass through an optical element 14, such as aconverging lens or the like, and then enters into a light detector 15.

The focus and tracking detector 13 is operative to produce outputsignals SF and ST which represent respectively the focus condition andthe tracking condition of the laser light beams incident upon theoptical tape 10 in response to the laser light beams incident upon thefocus and tracking detector 13 through the optical element 12. Theoutput signals SF and ST thus obtained from the focus and trackingdetector 13 are used for focus control and tracking control to whicheach of the laser light beams to be incident upon the optical tape 10 issubjected in the light beam control optical system 9.

The light detector 15 is operative to produce a plurality of outputsignals SI which vary in response to variations in each of the laserlight beams incident upon the light detector 15 through the opticalelement 14 and supply an information reproducing portion 16 with theoutput signals SI. The information reproducing portion 16 is operativeto reproduce the information recorded on the optical tape 10 based onthe output signals SI obtained from the light detector 15.

In the optical tape recording and reproducing apparatus thus shown inFIG. 1, when information is newly recorded on the optical tape 10, themodulation control signals SM which are produced to vary in response tothe information to be recorded are supplied from the modulation controlsignal generator 7 to the reflection type light-modulating elementsconstituting the two-dimensional light-modulator 6, respectively. As theresult, the laser light beams which are modulated in response to themodulation control signals SM by the reflection type light-modulatingelements and simultaneously reflected from the reflection typelight-modulating elements are obtained from the two-dimensionallight-modulator 6 to be directed to the converging lens 5.

The laser light beams modulated in response to the modulation controlsignals SM and obtained from the two-dimensional light-modulator 6 passthrough the converging lens 5, the quarter wavelength plate 4, thepolarized light beam splitter 3 and the quarter wavelength plate 8 toenter into the light beam control optical system 9 and then aresubjected to the focus control and the tracking control in the lightbeam control optical system 9 so as to be incident upon the optical tape10. As a result of this, the recording of the information on the opticaltape 10 is carried out with the laser light beams modulated in responseto the modulation control signals SM and the recording tracks, on eachof which the information is recorded, are formed on the optical tape 10.

When information recorded on the optical tape 10 is reproduced from theoptical tape 10 in the optical tape recording and reproducing apparatusshown in FIG. 1, the modulation control signals SM, each of which ispredetermined to be constant, are supplied from the modulation controlsignal generator 7 to the reflection type light-modulating elementsconstituting the two-dimensional light-modulator 6, respectively. As theresult, the laser light beams which are reflected with a constantreflecting amount without being modulated from the reflection typelight-modulating elements are obtained from the two-dimensionallight-modulator 6 to be directed to the converging lens 5.

The laser light beams having not been modulated and obtained from thetwo-dimensional light-modulator 6 pass through the converging lens 5,the quarter wavelength plate 4, the polarized light beam splitter 3 andthe quarter wavelength plate 8 to enter into the light beam controloptical system 9 and then are subjected to the focus control and thetracking control in the light beam control optical system 9 so as to beincident upon the optical tape 10. The laser light beams thus incidentupon the optical tape 10 are modulated in response to the informationrecorded on the optical tape 10 and simultaneously reflected from theoptical tape 10 to be directed to the light beam control optical system9. The laser light beams modulated in response to the informationrecorded on the optical tape 10 and obtained from the optical tape 10pass through the light beam control optical system 9 and the quarterwavelength plate 8 and then are reflected from the polarized light beamsplitter 3 to enter into the light beam splitter 11. The laser lightbeams thus entering into the light beam splitter 11 are partiallyreflected from the light beam splitter 11 to enter into the focus andtracking detector 13 and simultaneously partially pass through the lightbeam splitter 11 to enter into the light detector 15 through the opticalelement 14.

As a result of this, the output signal SF which represents the focuscondition of the laser light beams incident upon the optical tape 10 andthe output signal ST which represents the tracking condition of thelaser light beams incident upon the optical tape 10 are obtained fromthe focus and tracking detector 13 and the output signals SI which varyin response to variations in each of the laser light beams modulated inresponse to the information recorded on the optical tape 10 are obtainedfrom the light detector 15 to be supplied to the information reproducingportion 16. Then, in the information reproducing portion 16, theinformation recorded on the optical tape 10 is reproduced based on theoutput signals SI obtained from the light detector 15.

The optical tape 10 on which the information is recorded or from whichthe information recorded thereon is reproduced in the optical taperecording and reproducing apparatus shown in FIG. 1, is driven to run bythe optical tape driving device.

FIG. 2 shows an example of the optical tape driving device. In theoptical tape driving device shown in FIG. 2, a supply reel 21 on whichthe optical tape 10 is wound to be derived therefrom and a take-up reel22 onto which the optical tape 10 is wound are provided. The opticaltape 10 between the supply reel 21 and the take-up reel 22 is driven bya friction capstan 23 to run in the T direction from the supply reel 21to the take-up reel 22.

Further, in the optical tape driving device shown in FIG. 2, a pluralityof positioning members 24, a pair of tension regulators 25 and a runningguide member 26 are provided for causing the optical tape 10 driven bythe friction capstan 23 to run stably though a predetermined position.The positioning members 24 determine a running path for the optical tape10 and tension regulators 25 are operative to provide the optical tape10 between the supply reel 21 and the take-up reel 22 with predeterminedtensile force brought about by springs 27. The running guide member 26serves for guiding the optical tape 10 so that the laser light beamsobtained from a light beam controlling and signal processing portion 28,such as shown in FIG. 1, are incident upon the optical tape 10 on therunning guide member 26.

As shown in FIG. 3, the running guide member 26 has a guide face portion29 facing to the optical tape 10 and a flange portion 30 for restrictingthe position of the optical tape 10 running thought the guide faceportion 29. The guide face portion 29 is formed into a partialcylindrical surface as shown in FIG. 4.

The main function required to be performed by the running guide member26 in the optical tape driving device mentioned above is to maintain aspace between the optical tape 10 and the guide face portion 29 to beextremely small, for example, 10 to 100 nm (nanometer) for stabilizingthe position of the optical tape 10 running through the guide faceportion 29 so that the incident position on the optical tape 10 of eachof the laser light beams obtained from the light beam controlling andsignal processing portion 28 is fixed invariably.

However, with the running guide member 26 in the optical tape drivingdevice mentioned above, the optical tape 10 comes into concentrativecontact with a portion of the guide face portion 29 which is very narrowin the T direction and extends along the width of the optical tape 10because the guide face portion 29 is formed into the cylindrical surfaceas shown in FIG. 4 and therefore the space between the optical tape 10and the guide face portion 29 which is required to be extremely small,for example, 10 to 100 nm, is formed only on the very narrow portion ofthe guide face portion 29. This means that an area on the guide faceportion 29 where the incident position on the optical tape 10 of each ofthe laser light beams which are obtained from the light beam controllingand signal processing portion 28 is fixed invariably is limited to bevery narrow. Further, the portion of the guide face portion 29 withwhich the optical tape 10 comes into concentrative contact is subjectedto abrasion to be deformed and thereby it is feared that a disadvantagewherein the space between the optical tape 10 and the guide face portion29 required to be extremely small, for example, 10 to 100 nm, is variedis brought about.

Accordingly, it is an object of the invention disclosed in each ofclaims of the present application to provide an apparatus for driving atape-shaped optical recording medium which is provided with runningguide means having a guide face portion for facing to a tape-shapedoptical recording medium and capable of maintaining continuously a spacebetween the tape-shaped optical recording medium and the guide faceportion to be extremely small over a relatively wide area on the guideface portion and thereby is able to maintain stably an area on the guideface portion where the incident position on the tape-shaped opticalrecording medium of each of laser light beams obtained from a light beamcontrolling and signal processing portion is fixed invariably to berelatively wide.

DISCLOSURE OF THE INVENTION

According to the invention claimed in any one of claims 1 to 11 of thepresent application, there is provided an apparatus for driving atape-shaped optical recording medium, which comprises a pair of reelmeans for supplying with a tape-shaped optical recording medium and fortaking-up the tape-shaped optical recording medium, respectively,driving means for causing the tape-shaped optical recording medium torun from one of the reel means to the other of the reel means, andrunning guide means for guiding the tape-shaped optical recording mediumrunning between the reel means, wherein the running guide means has aflat portion forming a guide face portion for facing to the tape-shapedoptical recording medium and is operative to cause the tape-shapedoptical recording medium to run along the flat portion.

In the apparatus for driving a tape-shaped optical recording medium thusconstituted in accordance with the invention claimed in any one ofclaims 1 to 11 of the present application, since the guide face portionfor facing to the tape-shaped optical recording medium is formed withthe flat portion of the running guide means for guiding the tape-shapedoptical recording medium running between the reel means, a space betweenthe tape-shaped optical recording medium and the guide face portion isstably and continuously maintained to be very small over a relativelywide area on the flat portion of the running guide means. Consequently,when a light beam obtained from a light beam controlling and signalprocessing portion is incident upon the tape-shaped optical recordingmedium running between the reel means on the flat portion of the runningguide means, an area on the guide face portion where an incidentposition on the tape-shaped optical recording medium of the light beamobtained from the light beam controlling and signal processing portionis fixed invariably can be stably maintained to be relatively wide.

As a result, when the light beam obtained from the light beamcontrolling and signal processing portion is incident upon thetape-shaped optical recording medium running between the reel means onthe flat portion of the running guide means, a focus servo control forthe light beam which requires an undesirable high speed control inresponse to the running of the tape-shaped optical recording medium canbe unnecessary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a light beam controlling andsignal processing portion in an example of a optical tape recording andreproducing apparatus proposed previously;

FIG. 2 is a schematic structural illustration showing an essential partof an example of an optical tape driving device for driving an opticaltape on which information is recorded or from which information isreproduced by the light beam controlling and signal processing portionshown in FIG. 1;

FIG. 3 is a schematic side view used for explaining a running guidemember in the optical tape driving device shown in FIG. 2;

FIG. 4 is a schematic cross-sectional view used for explaining therunning guide member in the optical tape driving device shown in FIG. 2;

FIG. 5 is a schematic structural illustration showing an essential partof an embodiment of apparatus for driving a tape-shaped opticalrecording medium according to the invention claimed in any one of claims1 to 11 of the present application;

FIG. 6 is a schematic block diagram showing an example of an embodiedstructure of a light beam controlling and signal processing portion inthe embodiment shown in FIG. 5;

FIG. 7 is a schematic side view used for explaining a running guidemember in the embodiment shown in FIG. 5;

FIG. 8 is a schematic cross-sectional view used for explaining therunning guide member in the embodiment shown in FIG. 5;

FIG. 9 is a schematic cross-sectional view used for explaining a firstexample of the running guide member in the embodiment shown in FIG. 5;

FIG. 10 is a schematic side view used for explaining the first exampleof the running guide member in the embodiment shown in FIG. 5;

FIG. 11 is a schematic cross-sectional view used for explaining a secondexample of the running guide member in the embodiment shown in FIG. 5;

FIG. 12 is a schematic side view used for explaining the second exampleof the running guide member in the embodiment shown in FIG. 5;

FIG. 13 is a schematic cross-sectional view used for explaining a thirdexample of the running guide member in the embodiment shown in FIG. 5;

FIG. 14 is a schematic side view used for explaining the third exampleof the running guide member in the embodiment shown in FIG. 5;

FIG. 15 is a schematic block diagram showing a light beam controllingand signal processing portion used together with the third example ofthe running guide member in the embodiment shown in FIG. 5;

FIG. 16 is a schematic cross-sectional view used for explaining a fourthexample of the running guide member in the embodiment shown in FIG. 5;

FIG. 17 is a schematic side view used for explaining the fourth exampleof the running guide member in the embodiment shown in FIG. 5;

FIG. 18 is a schematic cross-sectional view used for explaining a fifthexample of the running guide member in the embodiment shown in FIG. 5;

FIG. 19 is a schematic side view used for explaining the fifth exampleof the running guide member in the embodiment shown in FIG. 5;

FIG. 20 is a schematic cross-sectional view used for explaining a sixthexample of the running guide member in the embodiment shown in FIG. 5;and

FIG. 21 is a schematic side view used for explaining the sixth exampleof the running guide member in the embodiment shown in FIG. 5.

EMBODIMENTS MOST PREFERABLE FOR WORKING OF THE INVENTION

FIG. 5 shows an essential part of an embodiment of apparatus for drivinga tape-shaped optical recording medium according to the inventionclaimed in any one of claims 1 to 11 of the present application.

In the embodiment shown in FIG. 5, a supply reel 41 on which an opticaltape 40 as an optical recording medium is wound to be derived therefromand a take-up reel 42 onto which the optical tape 40 is wound areprovided. The optical tape 40 between the supply reel 41 and the take-upreel 42 is driven by a friction capstan 43 to run in the directionindicated with an arrow T (the T direction) from the supply reel 41 tothe take-up reel 42.

Further, in the embodiment shown in FIG. 5, a plurality of positioningmembers 44, a pair of tension regulators 45 and a running guide member46 are provided for causing the optical tape 40 driven by the frictioncapstan 43 to run stably though a predetermined position. Thepositioning members 44 determine a running path for the optical tape 40and tension regulators 45 are operative to provide the optical tape 40between the supply reel 41 and the take-up reel 42 with predeterminedtensile force brought about by springs 47. The running guide member 46serves for guiding the optical tape 40 so that laser light beamsobtained from a light beam controlling and signal processing portion 48are incident upon the optical tape 40 on the running guide member 46.

The light beam controlling and signal processing portion 48 is embodiedin structure a shown in FIG. 6, for example. In the embodied structureof the light beam controlling and signal processing portion 48 shown inFIG. 6, a laser light source 51 is provided for generating continuously,for example, a plurality of laser light beams. The laser light beamsemitted from the laser light source 51 enter into an optical system 52which contains, for example, a collimating lens, to be collimatedthereby. The collimated laser light beams obtained from the opticalsystem 52 enter into a polarized light beam splitter 53 and arereflected from the polarized light beam splitter 53 to be directeddownward in FIG. 6 to pass through a quarter wavelength plate 54 andthen enter into a converging lens 55. The converging lens 55 isoperative to converge the collimated laser light beams having passedthrough the quarter wavelength plate 54 on a light-modulator 56.

The light-modulator 56 is constituted with, for example, a plurality ofreflection type light-modulating elements which are arrangedtwo-dimensionally. The laser light beams converged by the converginglens 55 come respectively to the reflection type light-modulatingelements so arranged two-dimensionally as to form the two-dimensionallight-modulator 56. A back surface of each of the reflection typelight-modulating elements, which is opposites to an incident surface ofthe reflection type light-modulating element upon which one of the laserlight beams is incident, forms a light reflector. Therefore, the laserlight beam incident upon each of the reflection type light-modulatingelements is reflected from the light reflector in the form of the backsurface of the reflection type light-modulating element.

In relation to the two-dimensional light-modulator 56, a modulationcontrol signal generator 57 is provided to be supplied with a signal SSrepresenting information for recording. The modulation control signalgenerator 57 is operative to produce a plurality of modulation controlsignals SMD which correspond to the information for recording inresponse to the signal SS or to produce a plurality of modulationcontrol signals SNM which are predetermined irrespectively of the signalSS and supply the reflection type light-modulating elements constitutingthe two-dimensional light-modulator 56 with the modulation controlsignals SMD or SNM, respectively.

When the modulation control signals SMD corresponding to the informationfor recording are supplied to the reflection type light-modulatingelements constituting the two-dimensional light-modulator 56, each ofthe reflection type light-modulating elements is operative to modulatethe laser light beam which is incident thereupon and reflected therefromin response to the modulation control signals SMD. The modulation towhich the laser light beam is thus subjected in the two-dimensionallight-modulator 56 is carried out by varying the reflection amount ofthe laser light beam at each of the reflection type light-modulatingelements in response to the modulation control signal SMD. On the otherhand, when the modulation control signals SNM are supplied to thereflection type light-modulating elements constituting thetwo-dimensional light-modulator 56, each of the reflection typelight-modulating elements is operative not to modulate the laser lightbeam which is incident thereupon to be reflected therefrom withsubstantially a constant reflection amount.

As a result of this, the laser light beams which are modulated inresponse to the modulation control signals SMD at and reflected from thereflection type light-modulating elements arranged two-dimensionally,respectively, or reflected respectively from the reflection typelight-modulating elements arranged two-dimensionally without beingmodulated, are obtained from the two-dimensional light-modulator 56 tobe directed to the converging lens 55.

The laser light beams obtained from the two-dimensional light-modulator56 pass through the converging lens 55 and the quarter wavelength plate54 to enter into the polarized light beam splitter 53. Since the laserlight beams entering into the polarized light beam splitter 53 from thequarter wavelength plate 54 have passed through the quarter wavelengthplate 54 twice in the direction to the converging lens 55 and in theopposite direction to the polarized light beam splitter 53, a plane ofpolarization of each of the laser light beams entering into thepolarized light beam splitter 53 from the quarter wavelength plate 54has been rotated by 90 degrees in comparison with that of each of thelaser light beams entering into the polarized light beam splitter 53from the optical system 52 and therefore the laser light beams enteringinto the polarized light beam splitter 53 from the quarter wavelengthplate 54 pass through the polarized light beam splitter 53 without beingreflected.

The laser light beams thus having passed through the polarized lightbeam splitter 53 further pass through a quarter wavelength plate 58 anda light beam control optical system 59 to be incident upon the opticaltape 40. The light beam control optical system 59 is operative tosubject each of the laser light beams passing through there to theoptical tape 40 to focus control for focusing properly each of the laserlight beams on the optical tape 40 and tracking control for causing eachof the laser light beams to be incident upon a proper position on theoptical tape 40.

When the laser light beams which have been modulated in response to themodulation control signals SMD at and reflected from the reflection typelight-modulating elements constituting the light-modulator 56 areincident upon the optical tape 40, a plurality of recording tracks, oneach of which the information for recording is recorded, are formed onthe optical tape 40 along its moving direction by the laser light beamsincident upon the optical tape 40. On the other hand, when the laserlight beams which have been reflected without being modulated from thereflection type light-modulating elements constituting thelight-modulator 56 are incident upon the optical tape 40, these laserlight beams trace continuously the recording tracks formed on theoptical tape 40 along its moving direction, respectively.

The laser light beams having been reflected without being modulated fromthe reflection type light-modulating elements constituting thelight-modulator 56 and incident upon the optical tape 40 to tracecontinuously the recording tracks formed thereon, are modulated inresponse to the information recorded on the recording tracks formed onthe optical tape 40 and simultaneously reflected from the optical tape40 to be directed to the light beam control optical system 59. The laserlight beams obtained from the optical tape 40 pass through the lightbeam control optical system 59 and the quarter wavelength plate 58 andthen enter into the polarized light beam splitter 53. Since the laserlight beams entering into the polarized light beam splitter 53 from thequarter wavelength plate 58 have passed through the quarter wavelengthplate 58 twice in the direction to the light beam control optical system59 and in the opposite direction to the polarized light beam splitter53, a plane of polarization of each of the laser light beams enteringinto the polarized light beam splitter 53 from the quarter wavelengthplate 58 has been rotated by 90 degrees in comparison with that of eachof the laser light beams entering into the polarized light beam splitter53 from the quarter wavelength plate 54 and therefore the laser lightbeams entering into the polarized light beam splitter 53 from thequarter wavelength plate 58 are reflected from the polarized light beamsplitter 53 to be directed to the right in FIG. 6.

The laser light beams reflected to the right in FIG. 6 from thepolarized light beam splitter 53 enter into a light beam splitter 61. Apart of each of the laser light beams having entered into the light beamsplitter 61 is reflected from the light beam splitter 61 to be directeddownward in FIG. 6 to pass through an optical element 62, such as acylindrical lens or the like, and then enters into a focus and trackingdetector 63 and another part of each of the laser light beams havingentered into the light beam splitter 61 passes through the light beamsplitter 61 further to pass through an optical element 64, such as aconverging lens or the like, and then enters into a light detector 65.

The focus and tracking detector 63 is operative to produce outputsignals SF and ST which represent respectively the focus condition andthe tracking condition of the laser light beams incident upon theoptical tape 40 in response to the laser light beams incident upon thefocus and tracking detector 63 through the optical element 62.

The output signals SF and ST thus obtained from the focus and trackingdetector 63 are used for focus control and tracking control to whicheach of the laser light beams to be incident upon the optical tape 40 issubjected in the light beam control optical system 59.

The light detector 65 is operative to produce a plurality of outputsignals SIN which vary in response to variations in each of the laserlight beams incident upon the light detector 65 through the opticalelement 64 and supply an information reproducing portion 66 with theoutput signals SIN. The information reproducing portion 66 is operativeto reproduce the information recorded on the optical tape 40 based onthe output signals SIN obtained from the light detector 65.

As shown in FIG. 7, the running guide member 46 has a guide face portion70 facing to the optical tape 40 and a flange portion 71 for restrictingthe position of the optical tape 40 running thought the guide faceportion 70. The guide face portion 70 is formed with a flat portion ofthe running guide member 46, as shown in FIG. 8, and the laser lightbeams emanating from the light beam controlling and signal processingportion 48 are incident upon the optical tape 40 on the flat portion ofthe running guide member 46 forming the guide face portion 70.

In a first example of the running guide member 46 having the flatportion which forms the guide face portion 70 facing to the optical tape40, as shown in FIGS. 7 and 8, the optical tape 40 runs along the flatportion of the running guide member 46 forming the guide face portion70, in such a manner as shown in FIGS. 9 and 10. As shown in FIG. 9, forexample, the running guide member 46 and the light beam control opticalsystem 59 in the light beam controlling and signal processing portion 48are positioned to be opposite to each other with the optical tape 40between them and the laser light beams having passed through the lightbeam control optical system 59 are incident directly upon the opticaltape 40 on the flat portion of the running guide member 46 forming theguide face portion 70.

When the optical tape 40 is driven to run in the T direction to theright edge 70R of the guide face portion 70 from the left edge 70L ofthe guide face portion 70 in FIGS. 9 and 10, an air flow going away fromthe optical tape 40 arises at the left edge 70L of the guide faceportion 70 in accordance with the movement of the optical tape 40, asshown with an arrow 72 in FIG. 9, so that air flowing onto the guideface portion 70 with the optical tape 40 running in the T direction isreduced, and to the contrary, air flowing out from the guide faceportion 70 at the right edge 70R of the guide face portion 70 with theoptical tape 40 running in the T direction, as shown with an arrow 73 inFIG. 9, is increased. Consequently, a negative pressure is induced onthe flat portion of the running guide member 46 forming the guide faceportion 70 and thereby a space between the guide face portion 70 and theoptical tape 40 is constantly and stably maintained to be extremelysmall, for example, 10 to 100 nm over a relatively wide area on theguide face portion 70 except portions in the vicinity of the right andleft edges 70R and 70L thereof.

Accordingly, with the running guide member 46 having the flat portionwhich forms the guide face portion 70 facing to the optical tape 40 andon which the laser light beams having passed through the light beamcontrol optical system 59 in the light beam controlling and signalprocessing portion 48 are incident upon the optical tape 40, asdescribed above, an area on the guide face portion 70 where an incidentposition on the optical tape 40 of each of the laser light beams havingpassed through the light beam control optical system 59 in the lightbeam controlling and signal processing portion 48 is fixed invariably isstably maintained to be relatively wide.

As a result, when the laser light beams having passed through the lightbeam control optical system 59 in the light beam controlling and signalprocessing portion 48 are incident upon the optical tape 40 on the flatportion of the running guide member 46 forming the guide face portion70, a focus servo control for the laser light beams incident upon theoptical tape 40 which requires an undesirable high speed control inresponse to the running of the optical tape 40 can be unnecessary.

Incidentally, even in the condition as mentioned above, it is fearedthat the focus condition of the laser light beams incident upon theoptical tape 40 is undesirably varied under the influence of, forexample, dispersions in manufacturing of various portions including therunning guide member 46 of the embodiment shown in FIG. 5 or variationsin temperature and aged deterioration in the embodiment shown in FIG. 5.Accordingly, it is desired to take a measure to providing a focuscontroller operative for the laser light beams incident upon the opticaltape 40 to absorb such variations in the focus condition of the laserlight beams incident upon the optical tape 40 as mentioned above so asto work as occasion demands whenever a power switch of the embodimentshown in FIG. 5 is turned on.

FIGS. 11 and 12 show a second example of the running guide member 46provided in the embodiment shown in FIG. 5.

In the second example of the running guide member 46 shown in FIGS. 11and 12, a part, for example, a central part of the flat portion formingthe guide face portion 70 is formed into a light transmittable portion75 constituted with glass or the like. This second example of therunning guide member 46 having the light transmittable portion 75 ispositioned between the optical tape 40 and the light beam controloptical system 59 in the light beam controlling and signal processingportion 48 shown in FIG. 5 and the laser light beams having passedthrough the light beam control optical system 59 further pass throughthe light transmittable portion 75 to be incident upon the optical tape40.

FIGS. 13 and 14 show a third example of the running guide member 46provided in the embodiment shown in FIG. 5.

As shown in FIG. 13, for example, the third example of the running guidemember 46 shown in FIGS. 13 and 14 and the light beam control opticalsystem 59 in the light beam controlling and signal processing portion 48are positioned to be opposite to each other with the optical tape 40between them and the laser light beams having passed through the lightbeam control optical system 59 are incident directly upon the opticaltape 40 on the flat portion of the running guide member 46 forming theguide face portion 70.

This third example of the running guide member 46 is provided with aplurality of through holes 76, each of which has one opening end on theflat portion forming the guide face portion 70. Each of the throughholes 76 is supplied through a nozzle 77 provided at the other openingend of each of the through holes 76 with compressed air Q, as shown inFIG. 13. The pressure by the compressed air 0 supplied to the throughholes 76 acts on the optical tape 40 running through the flat portionforming the guide face portion 70 so that a space 78 is formed betweenthe optical tape 40 and the flat portion forming the guide face portion70 facing to the optical tape 40, as shown in FIG. 13.

The supply of the compressed air 0 to the through holes 76 is carriedout by an air pump 79 as shown in FIG. 15 and the operation of the airpump 79 is controlled by a pump control signal CQ supplied to the airpump 79 from a control signal generator 80. The output signal SFrepresenting the focus condition of the laser light beams incident uponthe optical tape 40, which is obtained, together with the output signalST representing the tracking condition of the laser light beams incidentupon the optical tape 40, from the focus and tracking detector 63 in thelight beam controlling and signal processing portion 48, is supplied tothe control signal generator 80, as shown in FIG. 15.

The control signal generator 80 is operative to produce the pump controlsignal CQ varying in response to variations in the output signal SF fromthe focus and tracking detector 63 and supply the air pump 79 with thepump control signal CQ. Therefore, the compressed air Q supplied to thethrough holes 76 from the air pump 79 is controlled by the output signalSF representing the focus condition of the laser light beams incidentupon the optical tape 40 and obtained from the focus and trackingdetector 63 in the light beam controlling and signal processing portion48.

Consequently, the pressure by the compressed air Q acting on the opticaltape 40 running through the flat portion forming the guide face portion70 is controlled in response to the focus condition of the laser lightbeams incident upon the optical tape 40 and, as a result, the space 78formed between the optical tape 40 and the flat portion forming theguide face portion 70 facing to the optical tape 40 as shown in FIG. 13is adjusted in response to the focus condition of the laser light beamsincident upon the optical tape 40, so that the focus condition of thelaser light beams incident upon the optical tape 40 is appropriatelymaintained.

FIGS. 16 and 17 show a fourth example of the running guide member 46provided in the embodiment shown in FIG. 5.

As shown in FIG. 16, for example, the fourth example of the runningguide member 46 shown in FIGS. 16 and 17 and the light beam controloptical system 59 in the light beam controlling and signal processingportion 48 shown in FIG. 5 are also positioned to be opposite to eachother with the optical tape 40 between them and the laser light beamshaving passed through the light beam control optical system 59 areincident directly upon the optical tape 40 on the flat portion of therunning guide member 46 forming the guide face portion 70.

In this fourth example of the running guide member 46, the flat portionforming the guide face portion 70 is constituted with a porous materialmember 81. An air chamber forming portion 82 is provided at the side ofthe back surface of the porous material member 81 opposite to the frontsurface of the porous material member 81 facing to the optical tape 40and compressed air a is supplied through a nozzle 84 to an air chamber83 in the air chamber forming portion 82. The pressure by the compressedair Q supplied to the air chamber 83 acts through the porous materialmember 81 on the optical tape 40 running through the flat portionforming the guide face portion 70 so that a space 85 is formed betweenthe optical tape 40 and the flat portion forming the guide face portion70 facing to the optical tape 40, as shown in FIG. 16.

The controlled supply of the compressed air Q to the air chamber 83through the nozzle 84 is carried out in the same manner as that of thecompressed air Q to the through holes 76 in the third example of therunning guide member 46 shown in FIGS. 13 and 14. Consequently, thespace 85 formed between the optical tape 40 and the flat portion formingthe guide face portion 70 facing to the optical tape 40 as shown in FIG.16 is adjusted in response to the focus condition of the laser lightbeams having passed through the light beam control optical system 59 inthe light beam controlling and signal processing portion 48 shown inFIG. 5 to be incident upon the optical tape 40, so that the focuscondition of the laser light beams incident upon the optical tape 40 isappropriately maintained.

FIGS. 18 and 19 show a fifth example of the running guide member 46provided in the embodiment shown in FIG. 5.

In the fifth example of the running guide member 46 shown in FIGS. 18and 19, a part, for example, a central part of the flat portion formingthe guide face portion 70 is formed into a light transmittable portion75 constituted with glass or the like. Further, the fifth example of therunning guide member 46, which has the light transmittable portion 75 atthe central part of the flat portion forming the guide face portion 70,is provided with a plurality of through holes 76, each of which has oneopening end on the flat portion forming the guide face portion 70. Eachof the through holes 76 is supplied through a nozzle 77 provided at theother opening end of each of the through holes 76 with compressed air Q,as shown in FIG. 18. The pressure by the compressed air Q supplied tothe through holes 76 acts on the optical tape 40 running through theflat portion forming the guide face portion 70 so that a space 86 isformed between the optical tape 40 and the flat portion forming theguide face portion 70 facing to the optical tape 40, as shown in FIG.18.

The controlled supply of the compressed air Q to the through holes 76through the nozzle 77 is carried out in the same manner as that of thecompressed air Q to the through holes 76 in the third example of therunning guide member 46 shown in FIGS. 13 and 14. Consequently, thespace 86 formed between the optical tape 40 and the flat portion formingthe guide face portion 70 facing to the optical tape 40 as shown in FIG.18 is adjusted in response to the focus condition of the laser lightbeams having passed through the light beam control optical system 59 inthe light beam controlling and signal processing portion 48 shown inFIG. 5 to be incident upon the optical tape 40, so that the focuscondition of the laser light beams incident upon the optical tape 40 isappropriately maintained.

The fifth example of the running guide member 46 thus having the lighttransmittable portion 75 at the central part of the flat portion formingthe guide face portion 70 is positioned between the optical tape 40 andthe light beam control optical system 59 in the light beam controllingand signal processing portion 48 shown in FIG. 5 and the laser lightbeams having passed through the light beam control optical system 59further pass through the light transmittable portion 75 to be incidentupon the optical tape 40.

FIGS. 20 and 21 show a sixth example of the running guide member 46provided in the embodiment shown in FIG. 5.

In the sixth example of the running guide member 46 shown in FIGS. 20and 21, a part, for example, a central part of the flat portion formingthe guide face portion 70 is formed into a light transmittable portion75 constituted with glass or the like. Further, in this sixth example ofthe running guide member 46 which has the light transmittable portion 75at the central part of the flat portion forming the guide face portion70, both side parts of the flat portion forming the guide face portion70, between which the light transmittable portion 75 is provided, areconstituted with porous material members 81 a and 81 b, respectively.

An air chamber forming portion 82 a is provided at the side of the backsurface of the porous material member 81 opposite to the front surfaceof the porous material member 81 facing to the optical tape 40 andcompressed air Q is supplied through a nozzle 84 a to an air chamber 83a in the air chamber forming portion 82 a. Similarly, an air chamberforming portion 82 b is provided at the side of the back surface of theporous material member 81 b opposite to the front surface of the porousmaterial member 81 b facing to the optical tape 40 and compressed air Qis supplied through a nozzle 84 b to an air chamber 83 b in the airchamber forming portion 82 b.

The pressure by the compressed air Q supplied to the air chambers 83 aand 82 b acts through the porous material members 81 a and 81 b on theoptical tape 40 running through the flat portion forming the guide faceportion 70 so that a space 87 is formed between the optical tape 40 andthe flat portion forming the guide face portion 70 facing to the opticaltape 40, as shown in FIG. 20.

Each of the controlled supply of the compressed air Q to the air chamber83 a in the air chamber forming portion 82 a through the nozzle 84 a andthe controlled supply of the compressed air Q to the air chamber 83 b inthe air chamber forming portion 82 b through the nozzle 84 b is carriedout in the same manner as that of the compressed air Q to the throughholes 76 in the third example of the running guide member 46 shown inFIGS. 13 and 14. Consequently, the space 87 formed between the opticaltape 40 and the flat portion forming the guide face portion 70 facing tothe optical tape 40 as shown in FIG. 20 is adjusted in response to thefocus condition of the laser light beams having passed through the lightbeam control optical system 59 in the light beam controlling and signalprocessing portion 48 shown in FIG. 5 to be incident upon the opticaltape 40, so that the focus condition of the laser light beams incidentupon the optical tape 40 is appropriately maintained.

The sixth example of the running guide member 46 thus having the lighttransmittable portion 75 at the central part of the flat portion formingthe guide face portion 70 is positioned between the optical tape 40 andthe light beam control optical system 59 in the light beam controllingand signal processing portion 48 shown in FIG. 5 and the laser lightbeams having passed through the light beam control optical system 59further pass through the light transmittable portion 75 to be incidentupon the optical tape 40.

With each of the second to sixth examples of the running guide member 46shown in FIGS. 11 to 21, the advantages brought about by the flatportion of the running guide member 46 which forms the guide faceportion 70 facing to the optical tape 40 and on which the laser lightbeams having passed through the light beam control optical system 59 inthe light beam controlling and signal processing portion 48 are incidentupon the optical tape 40, are also obtained in the same manner as thoseobtained with the first example of the running guide member 46 shown inFIGS. 9 and 10.

APPLICABILITY FOR INDUSTRIAL USE

As apparent from the above description, in the apparatus for driving atape-shaped optical recording medium according to the invention claimedin any one of claims 1 to 11 of the present application, since the guideface portion for facing to the tape-shaped optical recording medium isformed with the flat portion of the running guide means for guiding thetape-shaped optical recording medium running between the reel means, aspace between the tape-shaped optical recording medium and the guideface portion is stably and continuously maintained to be very small overa relatively wide area on the flat portion of the running guide means.

Consequently, with the apparatus for driving a tape-shaped opticalrecording medium according to the invention claimed in any one of claims1 to 11 of the present application, when a light beam obtained from alight beam controlling and signal processing portion is incident uponthe tape-shaped optical recording medium running between the reel meanson the flat portion of the running guide means, an area on the guideface portion where an incident position on the tape-shaped opticalrecording medium of the light beam obtained from the light beamcontrolling and signal processing portion is fixed invariably can bestably maintained to be relatively wide. Further, as a result, when thelight beam obtained from the light beam controlling and signalprocessing portion is incident upon the tape-shaped optical recordingmedium running between the reel means on the flat portion of the runningguide means, a focus servo control for the light beam which requires anundesirable high speed control in response to the running of thetape-shaped optical recording medium can be unnecessary.

1. An apparatus for driving a tape-shaped optical recording mediumcomprising; a pair of reel means for supplying with a tape-shapedoptical recording medium and for taking-up the tape-shaped opticalrecording medium; driving means for causing the tape-shaped opticalrecording medium to run from one of said reel means to the other of saidreel means; and running guide means for guiding the tape-shaped opticalrecording medium running between said reel means, wherein said runningguide means has a flat portion forming a guide face portion for facingto the tape-shaped optical recording medium and is operative to causethe tape-shaped optical recording medium to run along the flat portion,and wherein said running guide means is provided with a lighttransmittable portion constituting a part of the flat portion thereofand positioned between the tape-shaped optical recording medium andoptical means for causing a light beam to be incident upon thetape-shaped optical recording medium so that said light beam is incidentupon the tape-shaped optical recording medium through said lighttransmittable portion.
 2. An apparatus for driving a tape-shaped opticalrecording medium comprising; a pair of reel means for supplying with atape-shaped optical recording medium and for taking-up the tape-shapedoptical recording medium; driving means for causing the tape-shapedoptical recording medium to run from one of said reel means to the otherof said reel means; and running guide means for guiding the tape-shapedoptical recording medium running between said reel means, wherein saidrunning guide means has a flat portion forming a guide face portion forfacing to the tape-shaped optical recording medium and is operative tocause the tape-shaped optical recording medium to run along the flatportion, wherein said running guide means is provided with a throughhole having an opening end thereof on the flat portion of said runningguide means and gas pressure supplying means is provided for causing gaspressure to act on the tape-shaped optical recording medium runningalong said flat portion through said through hole.
 3. An apparatus fordriving a tape-shaped optical recording medium according to claim 2,wherein said running guide means and optical means for causing a lightbeam to be incident upon the tape-shaped optical recording medium arepositioned to be opposite to each other with the tape-shaped opticalrecording medium between said running guide means and said optical meansand said light beam is incident upon the tape-shaped optical recordingmedium on the flat portion of said running guide means.
 4. An apparatusfor driving a tape-shaped optical recording medium according to claim 2,wherein said running guide means is provided with a light transmittableportion constituting a part of the flat portion thereof and positionedbetween the tape-shaped optical recording medium and optical means forcausing a light beam to be incident upon the tape-shaped opticalrecording medium so that said light beam is incident upon thetape-shaped optical recording medium through said light transmittableportion.
 5. An apparatus for driving a tape-shaped optical recordingmedium according to claim 2, wherein said gas pressure supplying meansincludes gas pressure controlling means for controlling the gas pressureacting on the tape-shaped optical recording medium running along theflat portion of said running guide means through the through hole havingthe opening end thereof on said flat portion so as to adjust a spacebetween the tape-shaped optical recording medium and the flat portion ofsaid running guide means.
 6. An apparatus for driving a tape-shapedoptical recording medium comprising; a pair of reel means for supplyingwith a tape-shaped optical recording medium and for taking-up thetape-shaped optical recording medium; driving means for causing thetape-shaped optical recording medium to run from one of said reel meansto the other of said reel means; and running guide means for guiding thetape-shaped optical recording medium running between said reel means,wherein said running guide means has a flat portion forming a guide faceportion for facing to the tape-shaped optical recording medium and isoperative to cause the tape-shaped optical recording medium to run alongthe flat portion, wherein said flat portion of the running guide meansis constituted with a porous material member and gas pressure supplyingmeans is provided for causing gas pressure to act on the tape-shapedoptical recording medium running along said flat portion through saidporous material member.
 7. An apparatus for driving a tape-shapedoptical recording medium according to claim 6, wherein said runningguide means and optical means for causing a light beam to be incidentupon the tape-shaped optical recording medium are positioned to beopposite to each other with the tape-shaped optical recording mediumbetween said running guide means and said optical means and said lightbeam is incident upon the tape-shaped optical recording medium on theflat portion of said running guide means.
 8. An apparatus for driving atape-shaped optical recording medium according to claim 6, wherein saidrunning guide means is provided with a light transmittable portionconstituting a part of the flat portion thereof and positioned betweenthe tape-shaped optical recording medium and optical means for causing alight beam to be incident upon the tape-shaped optical recording mediumso that said light beam is incident upon the tape-shaped opticalrecording medium through said light transmittable portion.
 9. Anapparatus for driving a tape-shaped optical recording medium accordingto claim 6, wherein said gas pressure supplying means includes gaspressure controlling means for controlling the gas pressure acting onthe tape-shaped optical recording medium running along the flat portionof said running guide means through said porous material memberconstituting said flat portion so as to adjust a space between thetape-shaped optical recording medium and said flat portion.